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Ozone and cigarette smoke worse for asthma than smoke alone

Ozone generators are often used in hotel rooms, cars and private homes to get rid of the smell of cigarette smoke, but new evidence suggests that this cure may be worse than the disease. Researchers at the Univeristy of California's Lawrence Berkeley National Laboratory have found that ozone combines with nicotine and other components of cigarette smoke to produce chemicals that are a greater asthma hazard than the original smoke. In particular, the chemicals combine to form ultrafine aerosols that can carry dangerous chemicals deep into the lungs, where they trigger the development of asthma.

Environmental chemist Mohamad Sleiman and his colleagues used the Advanced Light Source at the laboratory to monitor the interaction of ozone with nicotine and other components of cigarette smoke. They reported in the journal Atmospheric Environment that, to their surprise, the chemicals reacted to form the ultrafine aerosols -- smaller than those generated by smoking itself, and thus able to penetrate more deeply into the lungs. They also generated toxic compounds with a strong potential to stimualte asthma.

"The results predict that exposure to these ultrafine particles containing many oxidized species with high 'Asthma Hazard Indices' may increase the risks of asthma," Sleiman said in a statement. "Formation of ultrafine particles appears to be a key dynamic step in the transformation of secondhand smoke to thirdhand smoke."

The Berkeley group had reported earlier this year that smoking can deposit nicotine and other products on furniture and other surfaces, where it can be released over long periods of time. This so-called thirdhand smoke constitutes a previously unsuspected source of exposure to carcinogenic and asthma-inducing chemicals. Attempting to removethe residue with ozone -- which was thought to react with the chemicals and destroy them -- can apparently create even more hazardous compounds, the researchers found.

The study was funded by the Tobacco-Related Disease Research Program of the University of California Office of the President.